Braking device for gate



Ap 21, 1970 H. DURANT 3,507,368 7 BRAKING DEVICE FOR GATE Filed Feb. 21,1968 Hgnr/ DU/PAN,

law

United States Patent Int. Cl. F16d 55/02 US. Cl. 188-164 3 ClaimsABSTRACT OF THE DISCLOSURE A braking device for gates, particularly arailroad crossing gate comprising a disc, having a flat face, mounted onthe articulation shaft of the gate. An electromagnet is mounted in closerelationship with the flat face on a support mounted for articulationabout an axis parallel to the fiat face. The electromagnet includes atthe ends of the magnetic core a pair of pole pieces in the form ofplates the edges of which adjacent the disc flat face are provided withbrake linings. The articulation axis lies between the disc fiat face anda vertical through the center of gravity of the support and arranged tocause articulation of the support and electromagnet away from the discwhen the coil is deenergized.

The present invention relates to an electromagnetic braking deviceadapted to hold a gate, for instance a railroad crossing gate, inpredetermined positions by energization of a coil through which a DC.current flows.

The braking device according to the invention is particularlyappropriate to gates for full-width railroad crossings with automaticcontrol independent of signal blocks that regulate traffice on the road;any accidental break in the energization circuit of the braking deviceresulting in the fall of the gate. The braking device may oppose anappreciable torque while consuming very little power. There is hardlyany lateral forces reacting on the shaft of the driving motor forlifting the gate. Finally, the braking device is not bulky.

The braking device according to the invention is characterized in thatit comprises a flat circular disc mounted on the horizontal shaft of themotor device for lifting the gate, a support articulated about an axisparallel to the fiat face of the said disc, carrying a coil providedwith a magnetic core parallel to the said axis and having two polepieces in the form of parallel plates against the cheeks of the coil,the edges of the plates being disposed at a short distance from thedisc, provided outwardly with a thickness of Ferodo adapted to beapplied against the disc when the pole pieces are drawn toward it, thearticulation axis of the support being located between the verticalthrough the center of gravity of the support and the disc. -Z

The invention will be better understood from the following descriptionof a preferred embodiment having reference to the appended drawingillustrating a braking device according to the invention.

,The single figure is a perspective view illustrating a motor device 1adapted to actuate a non-illustrated gate and provided with a horizontalshaft 2. A circular disc 3 is mounted on shaft 2 and has a flat outerface located a short distance from the pole pieces 4 of an electromagnethaving a coil 6 surrounding a core 5. This electromagnet is mounted on asupport 7 that articulates about axle 8 solid with a bracket 9 securedto the frame of the motor device 1 by means of a U-shaped sheet metalmember .10 and screws (not shown on the drawing) for adjusting itsposition. A Ferodo brake lining 12 is provided Ill 3,507,368 PatentedApr. 21, 1970 on the outer edge of each pole piece 4, held thereagainstby a plate 13 secured by screws 14 to the pole piece. Brake lining 12projects beyond the edge of the pole piece 4 so that when the latter isdrawn toward disc 3, it is Ferodo lining that comes in contact with it.Safety lugs (not shown) made of non-magnetic metal prevent directcontact of the pole pieces with the disc when the Ferodo linings areworn out to a certain extent to thus avoid sticking. The articulationaxis 8 is located between the disc 3 and the vertical thruogh the centerof gravity of the support 7 in such a way that the weight of the latterdraws it away from the disc when the coil 6 is not energized. Anon-illustrated spring adds its action to that of gravity to draw thesupport away from the disc so as to give more stability to thisposition. This spring also serves to limit the pivoting movement of thesupport 7. It is secured to the latter by means of a screw 11 and, onthe other hand, fastened onto frame 10 by any other convenient means.

When coil 6 is energized by a DC. current, the pole pieces 4 are drawnby the disc 3 and apply their Ferodo linings whereby disc 3 is stoppedand, consequently, the gate. By braking the energization of coil 6, thegate falls back through its own weight while actuating its driving motorwhich, working as a generator, discharges through a resistance wherebyto smoothen the fall of the gate.

It is to be noted that, by the vertical orientation of the Ferodolinings, the braking forces practically result into two verticalcomponents equal and opposite to one another so that braking does notcreate appreciable forces on the driving axle.

I claim:

1. An electromagnetic braking device for a gate, particularly a railroadcrossing gate actuated by a motor having a horizontal shaft, comprising:i

(a) a magnetizable braking disc mounted on said shaft and having a flatface;

(b) an electromagnet including a coil, a magnetic core extending throughsaid coil and parallel to said braking disc and pole pieces in the formof j plates flat against each end of said core, said pole pieces eachhaving one edge adjacent said disc;

(0) brake lining on said edges to come against said disc when said coilis energized and said pole pieces are drawn towards said disc; and

(d) a support for said electromagnet, said support having anarticulation axis parallel to said disc and lying below the center ofgravity of said support, said articulation axis being located betweensaid disc and a vertical through said center of gravity whereby, upondeenergization of said coil, the weight of said support causes said polepieces to move away from said disc under the forces of gravity.

2. A braking device as claimed in claim .1, including means to restrictmovement of said .pole pieces away from said disc. 2

3. A braking device as claimed in claim 1, wherein said brake liningsare in the form of elongated parallel vertical strips disposed on eitherside of said motor shaft whereby to prevent the creation of anyappreciable lateral forces to act against said shaft.

References Cited UNITED STATES PATENTS 750,207 1/1904 Lockwood .5188-1641,812,190 6/1931 Baseler 1 1 88-164 X 2,131,888 10/1938 Harris.

DUANE A. REGER, Primary Examiner US. Cl. X.R. 188-71

